mysql智能存储过程

创建存储过程：

create procedure ordertotal(
       in onumber int,      
       in taxable boolean,      
       out ototal decimal(8,2)      
) COMMENT 'Obtain order total,optionally adding tax'
begin
     DECLARE total decimal(8,2);    
     declare taxrate int DEFAULT 6;    
     select sum(item_price * quantity) from orderitems where order_num = onumber into total;    
         
     if taxable then    
        select total+(total/100*taxrate) into total;       
     end if;    

     select total into ototal;    
end;

调用存储过程：taxable为真

call ordertotal(20005,1,@total);
select @total;

调用存储过程：taxable为假

call ordertotal(20005,1,@total);
select @total;